earth-wise guide toearth-wise guide to weeds...• resprouts from root • prefers moist areas in...

earth-wise guide to earth-wise guide to

Weeds

descriptionA weed is a plant that is growing where it is not wanted; it easily reproduces and spreads; competes with desirable plants for space, light and nutrition; detracts from the aesthetics of the landscape; can harbor pests and diseases

germinationWeed seeds may lie dormant, germinating when soil is disturbed and seeds are exposed to light; seeds may be windblown, spread by birds or introduced with imported soil

goalDisrupt the weed’s life cycle without damaging the environment

For assistance identifying weeds and choosing least toxic options, call the AgriLife Extension at512-854-9600

Least Toxic SolutionsPrevent Weeds• Keep plants healthy to help them out-

compete weeds • Do not let weeds flower or go to

seed – it greatly increases their potential population

• Do not bring soil with weed seeds or roots on site

• Use drip irrigation in beds to put water only where you want it – weeds will have a much harder time growing without water

• Monitor and remove weeds regularly before they get established

• Prevent weeds from growing by blocking light and/or creating a physical barrier to growth

Weed Barrier Options• Cover plant beds with 4-6”

of mulch• Cover soil with 4-6 sheets of

newspaper and cover with leaves to make a weed barrier in plant beds (lasts several months)

• Use weed control fabrics that allow water and air to reach plant roots (weeds may germinate in soil or fine-textured mulch on top of the fabric)

• Use a layer of cardboard covered with mulch for non-planted spaces like utility areas

• Avoid black plastic – it is non-biodegradable and reduces air exchange with roots

• Solarize new areas before planting to kill weeds and seeds (See Grow Green Installation and Maintenance fact sheet)

• Fill in pavement cracks with caulking compound formulated for asphalt or concrete

Physically Remove• Pull weeds regularly to keep

populations from getting out of hand • Weed by hand when practical• Pull or hoe weeds when plants are

small and the soil is moist • Use hoes designed to move

horizontally below the soil surface to avoid bringing seeds to the surface

• Be careful not to damage shallow- rooted landscape plants

Weed Disposal• Dispose of weeds that have

flowered or gone to seed in the trash

• Put vegetative structures like rhizomes (underground stems) from Johnsongrass and “nutlets” from nutsedge in the trash – not in the compost pile

Avoid using weed and

feed products because:• the best time to treat weeds is not

the best time to fertilize • broadcasting weed killer over

and entire lawn is usually overkill

Identify

before you buy

Need help diagnosing a

plant problem? Call the Texas

AgriLife Extension Service at

512-854-9600 and ask for the

Master Gardener desk

or email them at

[email protected]

DichondraDichondra repens

NutgrassesYellow NutsedgeCyperus esculentusPurple NutsedgeCyperus rotundus

• 1/2 to 3/4” kidney shaped leaves

• Inconspicuous in turf

• Grass-like in appearance• Has a triangular stem• Some rhizomes* terminate

in hard tubers (nutlets)

• Warm season perennial

• Seeds germinate in spring

• Emerges from nutlet in spring

• Creeping stems root where nodes contact the soil

• Seeds may stay dormant for years

• Grows in both sun and shade • Prefers fertile soil that is fre-

quently watered

• Spreads via rhizomes* and seeds

• Often reappears after a good summer rain

• Prefers sun• Sometimes introduced by soil

brought from off site

Broadleaf PlaintainPlantago major

• Rosette with large, rounded, wavy-edged leaves

• Greenish flowers on 5-10” stalks


• Seeds germinate early to late spring

• Reproduces by seed • Resprouts from root system• Prefers rich soil and moderately

wet areas

• Remove by hand or weed fork

• Be sure to remove the entire crown of the plant

DandelionTaraxacum officinale

• Rosette with lobed and serrated leaves

• Round , fluffy seed heads• Yellow flower• Milky sap

• Cool season perennial

• Seeds germinate in fall

• Reproduces by seed • Resprouts from root • Prefers moist areas in full sun• Edible

• Can easily be removed with a weed fork

• Must remove the taproot

• Shallow roots make it easy to remove by hand if soil is moist and loose

• Use a diamond, swan neck or stirrup hoe

Field BindweedConvolvulus arvensis

• Vine with 3-10’ long stems; can run along ground or climb

• Flower similar to Morning Glories

• Leaves are alternate with smooth edges


• Seeds germinate in spring and summer

• Reproduces by seed• Plant fragments of roots as short

as 2” can form new plants• Seeds may live in soil 60 years

• Dig out root with a weed fork to eliminate

• Repeat every 2 or 3 weeks or as soon as the bindweed reaches 6” in length

Poison IvyToxicodendron radicans

• Creeping or climbing woody vine

• Leaf edges may be smooth, wavy or serrated

• Alternate leaves with 3 leaflets

• Leafs out from deciduous stem in spring with onset of warm weather

• Reproduces by rhizomes* and seeds spread by birds

• Resprouts from root• Can cause rashes when dormant• Fumes from burning can cause

lung damage

• Wear gloves, long sleeves and long pants if removing manually

• Must eliminate roots

Bermudagrass Cynodon dactylon

• Fine-textured grass, often used as a turfgrass

• Becomes a weed when it starts creeping into land-scape beds


• Goes dormant with the onset of cold weather

• Spreads by seeds, rhizomes* and stolons**

• Spreads rapidly during hot times of year

• Grows in any soil; prefers full sun

• Use barriers that extend 8-10” below the surface

• Dig out as much of the roots and stolons** as possible with a Korean hoe

• May take several tries

DallisgrassPaspalum dilataum

• Low-growing, coarse- textured grass

• Light green leaves• Long seed heads on

tall stalks


• Seeds germinate in spring

• Grows faster than most turfgrasses

• Thrives in hot, humid conditions • Prefers moist soil• Tolerates sandy and clay soils

• Dig out crown of the plant and remove all of the stem with a weed fork

JohnsongrassSorghum halepense

• Wide leaf blade with white strip down the center

• Can grow up to 6’• Thick, creeping rhizomes*


• Reproduces by rhizomes* and seeds

• Stems root at the nodes• Sometimes introduced by soil

brought in from off site

• Take out as much of the rhizome as possible

• Persistent so may take several tries

QuackgrassElytrigia repens

• Grassy plant can grow 1-3.5’ tall

• Resembles wheat

• Evergreen • Reproduces by seed and rhizomes*

• Tolerates all types of soils

• Do not till -- broken segment of plants can root and sprout into new plants


• Thoroughly remove with a weed fork in the spring before nutlets form


PERENNIALS, BROADLEAF

PERENNIALS, GRASSY

PERENNIALS, SEDGE

Name Description GrowingSeason

Comments/Growing Conditions

Least ToxicSolutions

* rhizomes- underground stems **stolons- above ground stems

• Manually remove the root system

• Water thoroughly 1-2 days before digging to soften soil

• Remove flower or seed heads to prevent spreading

• Herbicides are more effective against young growing weeds

• Choose a product that is formu-lated to kill the specific weed (non-selective products will kill or set back any plants they come in contact with)

• Read and follow label directions• Spot treat problems when possible• Be aware that very aggressive

weeds may require more than one application

PERENNIAL SOLUTIONS

Least toxic solutions If you must use a weed killer...

Broadleaf Plaintain Bermudagrass

Dandelion Dallisgrass

Dichondra Johnsongrass

Field Bindweed Quackgrass

Poison Ivy Yellow Nutsedge

• Annual weeds germinate from seeds each year; usually mature in one growing season and die within 12 months

• Cool season annual seeds typi-cally begin germinating in late September and grow through the winter months; warm season annual seeds typically begin germinating in early March and grow through the spring and summer months

• Pull or mow before plants seed• Mulch beds before September

to suppress winter annuals early and before March to smother warm season annuals

ANNUAL SOLUTIONSGeneral habits

Carpetweed Spotted Spurge

Common Lambsquarters

Annual Bluegrass

Henbit

Large Crabgrass

Sandbur

Purslane Smooth Crabgrass

Chickweed

Least toxic solutions

• Use a string trimmer on more mature growth of broadleaf weeds

• Spot treat young plants with products that contain herbicidal soap or 20% acetic acid (vinegar)

• Post-emergent herbicides are more effective before a weed has flowered or gone to seed

• Pre-emergents that target cool season or winter annuals must be applied in mid-September before their seeds germinate

• Pre-emergents that target warm season or summer annuals must be applied late January before their seeds germinate

If you must use an herbicide...

Smooth CrabgrassDigitaria ischaemum

• Low-growing • 15” or shorter• Dull green leaves; some red-

dish-purple color appears on stems as it ages

• Warm season annual

• Seed germinates spring through fall

• Spreads seed and roots from nodes touching soil

• Most often found in turf; it will tolerate mowing and still produce seed

• Dig out crown of plant and remove all of the stem with a weed fork

• Mat-forming• Grows 12” tall• Pale green leaf blades• Produces seed stalk with

sharp burs


SandburCenchrus longispinus


• Seed germinates in spring

• Usually found on poor sandy soils

Carpetweed Mollugo verticillata

• Forms circular mats up to 20” wide

• Leaves grow in whorls around the stem



• Prolific seeder• Shallow taproot• Prefers fertile, dry, sandy soil

• Easy to remove with hoe

Common LambsquartersChenopodium album

• Low-growing in turf or sprawling and upright

• Wavy Leaves• Green flowers with white

mealy powder



• Thrives in rich, fertile soil• Edible

• Easy to pull by grab-bing base of plant

HenbitLamium amplexicaule

• Grows upright but can root at the nodes

• Rounded, serrated leaves• Square stems• Pale purple flowers

• Cool season annual• Seed germinates in

the fall; grows very little until late win-ter to early spring

• Fibrous shallow roots• Prefers good soil with high

moisture level• Edible

• Easy to hand pull

PurslanePortulaca eleracea

• Prostrate; branches from a central point

• Shiny, fleshy leaves and purple-red stems

• Inconspicuous yellow flowers


• Seed germinates in late spring

• Seed can remain viable up to 40 years

• Thrives in extremely hot, dry weather

• Edible

• Remove by hand• Put plant fragments in

trash because they can root

Spotted SpurgeEuphorbia maculatacaule

• Grows in dense mats• Reddish green to dark green

leaves with purple splotch on top

• Inconspicuous flowers


• Seed germinates in late spring to early summer

• Prolific seeder• Shallow taproot• Stem has milky sap

• Easy to hand pull or hoe

• Upright, clumping growth• Grows 4”-6” when not

mowed • Seed heads appear in mid to

late spring

• Insert weed fork into soil at the base of plant, then twist and remove

• Can grow to more than 3’ tall

• Pale, blue-green, sharply pointed leaves


Annual Bluegrass Poa annua

Large CrabgrassDigitaria sanguinalis

• Cool season annual • Seed germinates

in fall• Grows very little

until late winter


• Seed germinates spring to fall

• Prefers wet, compacted soils• Small clumps growing in lawn

makes it look uneven

• Spreads by seed and by long stems rooting at the nodes

• Single plant can produce 150,000 seeds/year

• Thrives in hot, dry conditions

ANNUALS, BROADLEAF

ANNUALS, GRASSY

Name DescriptionGrowingSeason

Comments/Growing Conditions

Least ToxicSolutions

Common ChickweedStellaria media

• Grows in thick mats• Small white flowers with

five petals• Shiny, pointed leaves

• Emerges in fall; grows very little until late winter

• Shallow, fibrous roots• Found most often in shady,

moist lawn areas

• Easy to hand pull

If you must use a weed killer...• Use herbicides only as a last resort

– they can end up in streams and aquifers. They may also damage desirable turf and landscape plants

• Spot treat existing problems with a selective post-emergent product

• Understand and choose the correct product

- Pre-emergents: prevent seeds from germinating – in general they are broadcast over a large area, most often used to control annual weeds; must be applied before targeted weed seeds germinate; use only if an area has a history of excessive weeds

- Post-emergents: kill weeds after they have emerged; most often used on perennial weeds – may require more than one applica-tion for stubborn perennials

- Non-selective post emergents: will kill or set back almost any plant they come in contact with

- Selective post-emergent herbi-cides: specifically formulated for certain types of weeds i.e. grassy weeds, broadleaf weeds, sedges and woody vegetation

• Don’t use an herbicide right before a rain – it can run off to harm our creeks rather than helping your yard

• Always follow the EPA-approved label directions

• Consult with your Extension Agent or nursery professional for more information

• Apply products at the proper time for effective control or prevention of weeds

• Use a wiper applicator or weed wand designed to apply herbicide directly on the vegetation for post-emergent, non-selective products to minimize drifting

• When using a sprayer, use low pres-sure and large droplets; apply when it is not windy

From Left to Right (Korean Hoe, Diamond Hoe, Swan Neck Hoe, Stirrup Oscillating Hoe, Stirrup Hoe, Standard Garden Hoe)

Weeding ToolsChoose a tool that causes the least amount of soil disturbance• Korean Hoe is shaped like a

plow; used to grub out larger weeds or for making a shallow trench

• A Diamond Hoe has a flat diamond shaped blade designed to move just below the soil surface

• A Swan-neck Hoe has a curved neck that positions it to skim just below the soil surface

• The Stirrup or Oscillating Hoe has a double-edged blade that slides back and forth, minimizing soil disturbance

• The Standard Garden Hoe has a a large blade that is set at a sharp angle to the ground for chopping through overgrown weeds

• A Collinear hoe has a angled handle and a narrow blade

Your Yard

to OurCreeks

Avoid Using Weed & Feed.Broadcasting herbicides is

usually excessive. Use standard fertilizer and hand-pull

or spot-treat weeds.

From

Resources Bio-Integral Resource Center (BIRC): 510-524-2567/ www.birc.org Texas AgriLife Extension:

http://agrilifeextension.tamu.edu/solutions/weed-control-turfgrass/ Weeds: Control Without Poison by Charles Walters

The Gardener’s Weed Book: Earth-Safe Controls by Barbara Pleasant Common Weeds of the United States by United States Agricultural

Research Service

The City of Austin and the Texas AgriLife Extension provide this information as a comparative reference only. Listing of a specific product trade name does not constitute an endorsement of its use. Many other pes-

ticides and pesticide products, other than those listed in these tables are available and may be suitable for use. Check labels carefully as trade names and active ingredients may change.

Products rated by Grady J. Glenn, Ph.D., B.C.E., of the Pesticide Safety Education Program, Texas AgriLife Extension Service. The rating system was developed by Philip Dickey of the Washington Toxics Coalition.

Pre-emergentConcern® Weed Prevention Plus™ 8-2-4 Corn gluten 100% d d c d ? ?Monterey Weed Impede™ Orzyalin 40.48% d d a d d dPreen® Garden Weed Preventer Trifluralin 1.47% c ? a c d cGreen Light® Amaze® Grass & Weed Killer Benefin 1%, Oryzalin 1% c a b b d b//a

Post-emergentGreen Light® Organic Spot Weeder 2-Phenethyl proprionate 2.5% Eugenol 2.5% d ? ? d d d

Bioganic™ Spot Weeder Ready-to-Use Phenethyl proprionate 2.5% Eugenol 2.5% d ? ? d d d

Ortho® Ecosense™ Brand Organic 2-Phenethyl proprionate 2.5% Weed & Grass Killer Eugenol 2.5% d ? ? d d d

Roundup® Weed and Grass Killer Glyphosate 2%, Pelargonic acid 2% Ready-to-Use Plus c ? c d d b

Eliminator® Weed & Grass Killer Glyphosate 2% c ? c d d bSedgeHammer Halosulfuron - methyl 75% c c c d b ?Ortho® Weed-B-Gon Max® Ready to Spray Triclopyr 1.56%, MCPA 13.72%, Dicamba 1.35% c c b c c d

Maestro Gro Vinegar Acetic acid/ Vinegar 20% a ? c d d dAmdro® Image® Nutsedge Killer Imazaquin 3.3% c ? c d a bEliminator® Liquid Edger Sodium cacodylate 0.53% Cacodylic acid 0.09% b a b b d b//aHi-Yield® Atrazine Weed Killer Atrazine 40.8%, Related compounds 2.2% c b b d a b/

Pre and Post-emergent (for pavement cracks)

Roundup® Extended Control Weed & Glyphosate 18%, Diquat 0.73% Grass Killer plus Preventer Concentrate Imazapic 0.3% c ? c d d b

Ortho® Season Long Max® Weed & Glyphosate 0.25% Grass Killer Plus Preventer Ready-to-Use Oxyfluorfen 0.25% c ? c d d b

acute

aquatic life

birds, bees, pets

soil mobility

environmentalpersistencechronic

human toxicityProduct Name

Hazards:

product toxicity comparisonsEvaluation of active ingredients only; does not include toxicity information on inert or “other” ingredients.

active ingredient(s) /concentrationsnote

most toxic

most toxic

most toxic

d low c low to moderate b high a highest NA not applicable

? unknown toxicity earth-wise

Toxicity/Threat:

09/16512-854-9600512-974-2550

Why Grow Green?

The Grow Green program is based on Integrated Pest Manage-

ment (IPM) principles that encourage the LEAST TOXIC approach to pesticide and fertilizer use. The goal is to reduce the amount of landscape chemicals that

degrade water quality when they run off into waterways or leach

into our groundwater.

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